E-M1 Playback glitches

Relatively new to the E-M1, but have had many prior Olympus mFT bodies. The rear dial zoom in playback is a great feature.

However, on my unit the rear dial often doesn't work - either there is a delay in zooming in or no zoom at all. Zooming out seems to work fine. I don't recall this happening prior to the firmware upgrade, but didn't have it that long before f 2.0. Removing and replacing the battery seems to help, but not power down/up. Software bug?

I haven't been able to find any other references to this behavior - anyone seen this behavior?